<!DOCTYPE html>
<html lang="en">
<!--<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>-->
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div id="app1">
  <p>{{a}}</p>
</div>
</body>
<script>
  var data = {a:1}
  var vm = new Vue({
    el: '#app1',
    data: data
  })
  vm.a = 2
  console.log(vm.a == data.a)
  console.log(data.a)
  data.a = 3
  console.log(vm.a)
  new Vue({
    data: {
      a: 1
    },
    created: function () {
      console.log('a is :'+ this.a)
    }
  })
</script>

</html>
